U.S. patent application number 14/417454 was filed with the patent office on 2015-07-16 for fuel cell, and fuel cell stack.
This patent application is currently assigned to NGK SPARK PLUG CO., LTD.. The applicant listed for this patent is NGK SPARK PLUG CO., LTD.. Invention is credited to Nobuyuki Hotta, Atsushi Mizuno, Tetsuya Morikawa, Ryoji Tanimura.
Application Number | 20150200404 14/417454 |
Document ID | / |
Family ID | 49996922 |
Filed Date | 2015-07-16 |
United States Patent
Application |
20150200404 |
Kind Code |
A1 |
Hotta; Nobuyuki ; et
al. |
July 16, 2015 |
FUEL CELL, AND FUEL CELL STACK
Abstract
A fuel cell (3) includes interconnectors (hereinafter, IC) (12,
13), a cell body (20) disposed between the ICs and including an air
electrode (14) and a fuel electrode (15) on both surfaces of an
electrolyte (2), and current collecting members (18, 19) disposed
between at least one of the electrodes (14, 15) and the ICs. The
current collecting members (19) include connector contact portions
(19a) in contact with the IC (13), cell body contact portions (19b)
in contact with the cell body, and connecting portions (19c) that
are bent approximately 180 degrees and connect both the contact
portions, the connector contact portions, the cell body contact
portions, and the connecting portions being formed in line. The
current collecting members (19) include asperities (19e) on inside
surfaces oriented inward, and a spacer (58) is disposed between the
connector contact portions and the cell body contact portions.
Inventors: |
Hotta; Nobuyuki; (Konan-shi,
JP) ; Tanimura; Ryoji; (Nagoya-shi, JP) ;
Mizuno; Atsushi; (Komaki-shi, JP) ; Morikawa;
Tetsuya; (Ichinomiya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NGK SPARK PLUG CO., LTD. |
Nagoya-shi, Aichi |
|
JP |
|
|
Assignee: |
NGK SPARK PLUG CO., LTD.
Nagoya-shi, Aichi
JP
|
Family ID: |
49996922 |
Appl. No.: |
14/417454 |
Filed: |
July 25, 2013 |
PCT Filed: |
July 25, 2013 |
PCT NO: |
PCT/JP2013/004530 |
371 Date: |
January 26, 2015 |
Current U.S.
Class: |
429/452 ;
429/508; 429/535 |
Current CPC
Class: |
H01M 8/0273 20130101;
H01M 2008/1293 20130101; H01M 8/2475 20130101; H01M 8/2484
20160201; H01M 8/0206 20130101; H01M 8/0202 20130101; Y02E 60/50
20130101; H01M 8/2425 20130101; H01M 8/2483 20160201 |
International
Class: |
H01M 8/02 20060101
H01M008/02; H01M 8/24 20060101 H01M008/24 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 27, 2012 |
JP |
2012-166612 |
Claims
1. A fuel cell comprising: a pair of interconnectors; a cell body
disposed between the interconnectors, and including an air
electrode on one surface of an electrolyte and a fuel electrode on
the other surface; and a current collecting member disposed between
at least one of the air electrode and the fuel electrode, and the
interconnectors, and arranged to electrically connect the air
electrode and/or the fuel electrode with the interconnectors,
wherein the current collecting member comprises a connector contact
portion that is in contact with the interconnector, a cell body
contact portion that is in contact with the cell body, and a
connecting portion that is bent approximately 180 degrees and
connects the connector contact portion and the cell body contact
portion, the connector contact portion, the cell body contact
portion and the connecting portion being formed in line, and the
current collecting member comprising asperities having surface
roughness of which ten-point average roughness is Rz.gtoreq.4 .mu.m
on an inside surface that is oriented inward in a state where the
current collecting member is bent, and wherein the fuel cell
comprises a spacer disposed between the connector contact portion
and the cell body contact portion that are opposed to each other
between the cell body and the interconnector.
2. The fuel cell according to claim 1, wherein the current
collecting member is made of metallic foil made in an
electroplating method.
3. The fuel cell according to claim 1, wherein the current
collecting member has a thickness of 15 to 100 .mu.m.
4. The fuel cell according to claim 1, wherein the current
collecting member is made of metallic foil of which the inside
surface is subjected to any one of sandblasting and etching.
5. A fuel cell stack comprising: a plurality of the fuel cells
according to claim 1, wherein the fuel cells are stacked and are
fixed by a clamping member.
6. A method for producing a fuel cell, the fuel cell comprising: a
pair of interconnectors; a cell body including an air electrode on
one surface of an electrolyte and a fuel electrode on the other
surface; a current collecting member made of a metallic flat plate
having a front surface and a back surface; and a spacer, the method
comprising the steps of: disposing the cell body between the pair
of interconnectors; preparing the current collecting member made of
the metallic flat plate having the back surface that has surface
roughness of which ten-point average roughness is larger than the
front surface; assembling the spacer and the metallic flat plate to
prepare the current collecting member in which the spacer is
incorporated; and disposing the current collecting member on which
the spacer is incorporated between the interconnectors and at least
one of the air electrode and the fuel electrode of the cell body,
wherein in the step of assembling the spacer and the metallic flat
plate to prepare the current collecting member in which the spacer
is incorporated, the back surface of the metallic flat plate is
brought into contact with the spacer to assemble the spacer and the
metallic flat plate.
7. The method for producing a fuel cell according to claim 6, the
method comprising the steps of: making a cutoff line to form a
segment in the metallic flat plate, and bending to raise the
segment from the metallic flat plate; and disposing the spacer on
the metallic flat plate, and sandwiching the spacer between the
segment and the metallic flat plate to form the current collecting
member.
8. The method for producing a fuel cell according to claim 6, the
method comprising the steps of: making a cutoff line to form a
segment in the metallic flat plate, and bending a portion of the
segment into a U-shape so that the segment covers the metallic flat
plate to form the current collecting member; and disposing the
spacer between the metallic flat plate and the segment.
9. The method for producing a fuel cell according to claim 6,
wherein the back surface of the metallic flat plate has surface
roughness of which ten-point average roughness Rz is Rz.gtoreq.4
.mu.m.
Description
TECHNICAL FIELD
[0001] The present invention relates to a fuel cell including two
electrodes on both surfaces of an electrolyte layer, and configured
to generate electric power by supplying a fuel gas to one of the
electrodes (hereinafter, referred to as a fuel electrode) while
supplying an oxidant gas to the other electrode (hereinafter,
referred to as an air electrode), and a fuel cell stack including a
plurality of the fuel cells stacked and fixed.
BACKGROUND ART
[0002] Conventionally, as described in Patent Literature 1 for
example, there is a fuel cell including a pair of interconnectors,
a cell body disposed between the interconnectors and including an
air electrode on one surface of an electrolyte and a fuel electrode
on the other surface, and a current collecting member disposed
between the air electrode and the interconnector or between the
fuel electrode and the interconnector and arranged to electrically
connect the air electrode and the interconnector or the fuel
electrode and the interconnector.
[0003] The current collecting member of this fuel cell has a
structure that claw-shaped elastic members are cut to be raised
from a current collecting plate having a flat plate shape, and is
arranged to perform electrical connection by joining a flat surface
of the current collecting plate to the interconnector via, for
example, a conductive paste and bringing the tips of the cut and
raised elastic members into contact with the cell body by the
elasticity of the elastic members themselves.
CITATION LIST
Patent Literature
[0004] Patent Literature 1: JP-A-2009-266533
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0005] The current collecting member that brings the elastic
members having conductivity into contact with the cell body by the
elasticity of the elastic members as in the conventional technique
cannot sometimes obtain a contact force for obtaining predetermined
electrical connection since the current collecting member is
plastically deformed in long-term use, and the elastic member
having conductivity deteriorates its strength due to high heat
during power generation, and further the elastic member having
conductivity comes under the influence of creep deformation. In
such a case, the elastic members having conductivity can no longer
follow the deformation of the cell body due to fluctuations of the
temperature cycle and/or the fuel pressure/air pressure, which
causes uncertain contact and results in uncertain electric
connection between the air electrode and the interconnector, or
between the fuel electrode and the interconnector.
[0006] In addition, when the above-described factors, reducing the
contact force to be required for obtaining electrical connection of
the elastic members, comes to be complex ones, the portions of the
elastic members that are to be in contact with the cell body may be
brought into contact with the interconnector side in reverse.
Meanwhile, the current collecting member is often made from a
material having excellent joining characteristics to the
interconnector since its flat surface is joined to the
interconnector. Hence, being brought into contact with the
interconnector side under the high temperature environment during
power generation, the elastic members could be joined to the
interconnector by sintering. In such a case, it is difficult for
the elastic members to be brought into contact with the cell body
since the elastic members are integrated with the interconnector,
which could cause uncertain electric connection between the air
electrode and the interconnector, or between the fuel electrode and
the interconnector.
[0007] The present invention is made in view of the above problems,
and an object of the present invention is to provide a fuel cell
and a fuel cell stack that are capable of maintaining favorable
electrical connection even in long-term use.
Means for Solving the Problem
[0008] In order to achieve the above object, as described in claim
1, the present invention provides a fuel cell comprising:
[0009] a pair of interconnectors;
[0010] a cell body disposed between the interconnectors, and
including an air electrode on one surface of an electrolyte and a
fuel electrode on the other surface; and
[0011] a current collecting member disposed between at least one of
the air electrode and the fuel electrode, and the interconnectors,
and arranged to electrically connect the air electrode and/or the
fuel electrode with the interconnectors,
[0012] wherein the current collecting member comprises a connector
contact portion that is in contact with the interconnector, a cell
body contact portion that is in contact with the cell body, and a
connecting portion that is bent approximately 180 degrees and
connects the connector contact portion and the cell body contact
portion, the connector contact portion, the cell body contact
portion and the connecting portion being formed in line, and the
current collecting member comprising asperities having surface
roughness of which ten-point average roughness is Rz.gtoreq.4 .mu.m
on an inside surface that is oriented inward in a state where the
current collecting member is bent, and
[0013] wherein the fuel cell comprises a spacer disposed between
the connector contact portion and the cell body contact portion
that are opposed to each other between the cell body and the
interconnector.
[0014] Further, as described in claim 2, the fuel cell according to
claim 1, wherein the current collecting member is made of metallic
foil made in an electroplating method.
[0015] Further, as described in claim 3, the present invention
provides the fuel cell according to claim 1 or 2, wherein the
current collecting member has a thickness of 15 to 100 .mu.m.
[0016] Further, as described in claim 4, the present invention
provides the fuel cell according to claim 1 or 3, wherein the
current collecting member is made of metallic foil of which the
inside surface is subjected to any one of sandblasting and
etching.
[0017] Further, as described in claim 5, the present invention
provides a fuel cell stack comprising: a plurality of the fuel
cells according to any one of claims 1 to 4, wherein the fuel cells
are stacked and are fixed by a clamping member.
[0018] Further, as described in claim 6, the present invention
provides a method for producing a fuel cell, the fuel cell
comprising: a pair of interconnectors; a cell body including an air
electrode on one surface of an electrolyte and a fuel electrode on
the other surface; a current collecting member made of a metallic
flat plate having a front surface and a back surface; and a spacer,
the method comprising the steps of: disposing the cell body between
the pair of interconnectors; preparing the current collecting
member made of the metallic flat plate having the back surface that
has surface roughness of which ten-point average roughness is
larger than the front surface; assembling the spacer and the
metallic flat plate to prepare the current collecting member in
which the spacer is incorporated; and disposing the current
collecting member on which the spacer is incorporated between the
interconnectors and at least one of the air electrode and the fuel
electrode of the cell body, wherein in the step of assembling the
spacer and the metallic flat plate to prepare the current
collecting member in which the spacer is incorporated, the back
surface of the metallic flat plate is brought into contact with the
spacer to assemble the spacer and the metallic flat plate.
[0019] Further, the present invention provides the method for
producing a fuel cell according to claim 6, the method comprising
the steps of: making a cutoff line to form a segment in the
metallic flat plate, and bending to raise the segment from the
metallic flat plate; and disposing the spacer on the metallic flat
plate, and sandwiching the spacer between the segment and the
metallic flat plate to form the current collecting member.
[0020] Further, the present invention provides the method for
producing a fuel cell according to claim 6, the method comprising
the steps of: making a cutoff line to form a segment in the
metallic flat plate, and bending a portion of the segment into a
U-shape so that the segment covers the metallic flat plate to form
the current collecting member; and disposing the spacer between the
metallic flat plate and the segment.
[0021] Further, the present invention provides the method for
producing a fuel cell according to any one of claims 6 to 8,
wherein the back surface of the metallic flat plate has surface
roughness of which ten-point average roughness Rz is Rz.gtoreq.4
.mu.m.
Advantageous Effects of Invention
[0022] According to the fuel cell of the present invention, the
spacer suppresses the connector contact portion and the cell body
contact portion from being deformed in an opposite contact
direction, so that the connector contact portion and the cell body
contact portion are not plastically deformed easily. Further, the
connector contact portion and the cell body contact portion are
more likely to be tolerated to the strength reduction which is
caused by high heat generated during the power generation, or creep
deformation. In addition, since the spacer is disposed between the
connector contact portion and the cell body contact portion of the
current collecting member to prevent them from being brought into
contact with each other, there is no possibility that the connector
contact portion and the cell body contact portion join together by
sintering. Therefore, integration of the connector contact portion
and the cell body contact portion, and destabilization in
electrical connection accompanied thereby can be prevented.
[0023] In addition, in the fuel cell according to the present
invention, since the spacer is disposed between the connector
contact portion and the cell body contact portion, and the
asperities having surface roughness of which ten-point average
roughness is Rz.gtoreq.4 .mu.m are in contact with both the
surfaces of the spacer, a large friction force is applied between
the connector contact portion and the spacer, and between the cell
body contact portion and the spacer. Thus, the spacer disposed
between the connector contact portion and the cell body contact
portion is prevented from being positionally deviated even when
undergoing vibration produced by, for example, transportation,
handling, or the like during an assembly process. As a matter of
course, positional deviation can be prevented by carefully
performing the assembly process; however, production efficiency is
decreased in such a case. It is to be noted that if the spacer is
positionally deviated with respect to the connector contact portion
and the cell body contact portion, not only the above-described
effect produced by providing the spacer could become insufficient,
but also the spacer could interfere with the cell body to cause a
cell crack when a plurality of fuel cells are stacked to be
clamped, which is not favorable. It is to be noted that the
measuring method of ten-point average roughness Rz of surface
roughness is in accordance with the JIS B0601:2001. (However,
ten-point average roughness Rz of surface roughness described in
the present application specifies "ten-point average roughness of
surface roughness", and ten-point average roughness of surface
roughness may be sometimes expressed as Rz or Rzj is depending on
the definitions determined by the JIS.) In addition, when the
ten-point average roughness Rz of the surface roughness of the
current collecting member is measured after the fuel cell is
assembled to operate, a portion that is not in contact with the
cell body, the interconnector, or the spacer, for example, a
connecting portion 19c of the current collecting member is cut off,
and the ten-point average roughness Rz of the surface roughness of
the surface of the connecting portion 19c on the side where the
current collecting member is in contact with the spacer can be
measured in accordance with the JIS B0601:2001.
[0024] The metallic foil made in the electroplating method
inherently includes asperities on one side, so that using such
metallic foil as the current collecting member as described in
claim 2 brings about cost saving.
[0025] It is also preferable that the thickness of the current
collecting member may be in a range of 15 to 100 .mu.m as described
in claim 3. If the current collecting member is thinner than 15
.mu.m, the current collecting member cannot easily obtain necessary
strength, and has electrical resistance increased. In addition, if
the current collecting member is thicker than 100 .mu.m, a
repelling force of bending the connecting portion 180 degrees
becomes excess, which could cause the cell body to crack at the
time of assembly.
[0026] The asperities of the current collecting member can be
formed by sandblasting or etching as described in claim 4.
[0027] In addition, including the plurality of the fuel cells
according to any one of claims 1 to 4 that are stacked and fixed by
the clamping member, the fuel cell stack described in claim 5 can
maintain favorable electrical connection even in long-term use.
[0028] In addition, according to the method for producing a fuel
cell of the present invention, since the surface of the current
collecting member made of the metallic flat plate, the surface
having the surface roughness of which ten-point average roughness
is larger, is brought into contact with both the surfaces of the
spacer, a large friction force is applied between the current
collecting member and the spacer. Thus, the spacer disposed between
the connector contact portion and the cell body contact portion of
the current collecting member is prevented from being positionally
deviated even when undergoing vibration produced by, for example,
transportation, handling, or the like during an assembly
process.
[0029] In addition, according to the method for producing a fuel
cell according to claim 7, since the cutoff line is made to form
the segment in the metallic flat plate, and after the segment was
bent to be raised, the spacer is disposed on the metallic flat
plate to sandwich the spacer between the segment and the metallic
flat plate, positioning of the spacer can be made relative to the
bent and raised segment, which facilitates mounting of the spacer
on the current collecting member.
[0030] In addition, according to the method for producing a fuel
cell according to claim 8, since the cutoff line is made to form
the segment in the metallic flat plate, and the segment is bent
into a U-shape to form the current collecting member, positioning
of the spacer can be made relative to the segment bent into a
U-shape, which facilitates mounting of the spacer on the current
collecting member.
[0031] In addition, according to the method for producing a fuel
cell according to claim 9, since the surface of the current
collecting member, the surface being in contact with the spacer,
has the surface roughness of which the ten-point average roughness
is Rz.gtoreq.4 .mu.m, a large friction force is applied between the
current collecting member and the spacer, and the current
collecting member and the spacer are prevented from being
positionally deviated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a perspective view of a fuel cell stack
structure.
[0033] FIG. 2 is a perspective view of a fuel cell.
[0034] FIG. 3 is an exploded perspective view of the fuel cell.
[0035] FIG. 4 is an exploded perspective view of the fuel cell
showing only narrowed parts.
[0036] FIG. 5 is a longitudinal sectional view of the fuel cell
where the middle portion is omitted.
[0037] FIG. 6 is a longitudinal sectional view showing FIG. 5 that
is disassembled.
[0038] FIG. 7 is a sectional view taken along the line A-A of FIG.
5.
[0039] FIG. 8 is a sectional view taken along the line B-B of FIG.
5.
[0040] FIG. 9 is a perspective view of a current collecting
member.
[0041] FIG. 10(a) is a perspective view of a spacer, and FIG. 10
(b) is a perspective view of the current collecting member on which
the spacer is yet to be mounted.
[0042] FIG. 11 is a perspective view of the current collecting
member that is a modified embodiment of FIG. 10(b).
[0043] FIG. 12 is a cross-sectional view of the current collecting
member in which an enlarged view of main parts is included.
MODES FOR CARRYING OUT THE INVENTION
[0044] At present, a fuel cell falls roughly into four types
depending on the material of the electrolyte: a polymer electrolyte
fuel cell (PEFC) in which a polyelectrolyte film is used as an
electrolyte, a phosphoric acid type fuel cell (PAFC) in which a
phosphoric acid is used as an electrolyte, a molten carbonate fuel
cell (MCFC) in which Li--Na/K carbonate is used as an electrolyte,
and a solid oxide fuel cell (SOFC) in which, for example,
ZrO2-based ceramic is used as an electrolyte. The fuel batteries of
four types are different in operating temperature (the temperature
at which ions can move in an electrolyte), and at present, the
operating temperature of the PEFC is room temperature to about
90.degree. C., the operating temperature of the PAFC is about
150.degree. C. to 200.degree. C., the operating temperature of the
MCFC is about 650.degree. C. to 700.degree. C., and the operating
temperature of the SOFC is about 700.degree. C. to 1000.degree.
C.
[0045] A fuel cell stack structure 1 defines an SOFC, in which, for
example, ZrO2-based ceramic is used as an electrolyte 2. The fuel
cell stack structure 1 generally includes a fuel cell 3 that is a
smallest power generation unit, an air supply passage 4 for
supplying air to the fuel cell 3, an air discharge passage 5 for
discharging the air to the outside, a fuel supply passage 6 for
supplying a fuel gas to the fuel cell 3 in a similar manner, a fuel
discharge passage 7 for discharging the fuel gas to the outside,
fixing members 9 for fixing a cell group that is prepared by
stacking a plurality of sets of the fuel cells 3 to form a fuel
cell stack 8, a container 10 for housing the fuel cell stack 8, and
output members 11 for outputting electricity generated in the fuel
cell stack 8.
[Fuel Cell]
[0046] The fuel cell 3 is square in a plan view, and includes as
shown in FIG. 3 a top interconnector 12 (* "top" or "bottom" in the
present description is based on the drawings, which are referred to
for the sake of illustration, and do not mean the absolute vertical
orientation. The same shall apply hereinafter.) that is made of
ferritic stainless steel having conductivity or the like in a
square plate shape, a bottom interconnector 13 that is made as well
of ferritic stainless steel or the like in a square plate shape, a
cell body 20 disposed nearly midway between the top and bottom
interconnectors 12 and 13 and including an air electrode 14
disposed on a surface of the electrolyte 2 opposed to an inner
surface (lower surface) of the top interconnector 12, a fuel
electrode 15 disposed on a surface of the electrolyte 2 opposed to
an inner surface (upper surface) of the bottom interconnector 13,
an air chamber 16 formed between the top interconnector 12 and the
air electrode 14, a fuel chamber 17 formed between the bottom
interconnector 13 and the fuel electrode 15, current collecting
members 18 on the side of the air electrode 14, the current
collecting members 18 being disposed inside the air chamber 16 and
arranged to electrically connect the air electrode 14 and the top
interconnector 12, and current collecting members 19 on the side of
the fuel electrode 15, the current collecting members 19 being
disposed inside the fuel chamber 17 and arranged to electrically
connect the fuel electrode 15 and the bottom interconnector 13, and
in the corners of the square, corner through-holes 47, 47 . . . ,
through which clamping members 46a to 46d to be described later of
the above-described fixing members 9 pass, are formed so as to
penetrate.
[Electrolyte]
[0047] The electrolyte 2 is made from LaGaO3-based ceramic,
BaCeO3-based ceramic, SrCeO3-based ceramic, SrZrO3-based ceramic,
CaZrO3-based ceramic, or the like in addition to the ZrO2-based
ceramic.
[Fuel Electrode]
[0048] Examples of a material of the above-described fuel electrode
15 include a mixture of a metal such as Ni and Fe, and at least one
of ceramics such as ZrO2-based ceramic such as zirconia that is
stabilized by at least one kind of rare earth elements such as Sc
and Y, and CeO2-based ceramic. In addition, the material of the
above-described fuel electrode 15 may be a metal such as Pt, Au,
Ag, Pb, Ir, Ru, Rh, Ni, and Fe, and only one kind of these metals
may be used, or two or more kinds of these metals may be used as an
alloy. Further, the examples of the material include a mixture
(including a cermet) of these metals and/or alloys, and at least
one kind of the above-described ceramics. In addition, the examples
of the material include a mixture or the like of an oxide of a
metal such as Ni and Fe, and at least one kind of the
above-described ceramics.
[Air Electrode]
[0049] Examples of a material of the above-described air electrode
14 include a variety of metals, oxides of metals, multiple oxides
of metals, and the like.
[0050] Examples of the above-described metals include metals such
as Pt, Au, Ag, Pb, Ir, Ru and Rh, or alloys containing two or more
kinds of metals.
[0051] Further, examples of the oxides of metals include oxides of
La, Sr, Ce, Co, Mn, Fe, and the like (La2O3, SrO, Ce2O3, Co2O3,
MnO2, FeO, and the like).
[0052] In addition, examples of the multiple oxides include
multiple oxides containing at least La, Pr, Sm, Sr, Ba, Co, Fe, Mn,
and the like (Lal-XSrXCoO3-based multiple oxide, Lal-XSrX
FeO3-based multiple oxide, Lal-XSrXCol-yFeO3-based multiple oxide,
Lal-XSrXMnO3-based multiple oxide, Prl-XBaXCoO3-based multiple
oxide, Sml-XSrXCoO3-based multiple oxide, and the like).
[Fuel Chamber]
[0053] The above-described fuel chamber 17 is formed into a square
chamber shape by an insulation frame 21 having a frame shape for
forming a fuel electrode gas passage (hereinafter, also referred to
as the "fuel electrode insulation frame 21") that is disposed on
the upper surface of the bottom interconnector 13 so as to surround
the current collecting members 19, and a fuel electrode frame 22
having a frame shape that is disposed on the upper surface of the
fuel electrode insulation frame 21 as show in FIG. 3 to FIG. 5.
[Current Collecting Members on the Side of a Fuel Chamber]
[0054] The current collecting members 19 on the side of the fuel
chamber 17 are made of, for example, Ni foil having a thickness of
15 to 100 .mu.m, and include connector contact portions 19a that
are in contact with the bottom interconnector 13, cell body contact
portions 19b that are in contact with the fuel electrode 15 of the
cell body 20, and connecting portions 19c having a U-shape that are
bent 180 degrees and connect the connector contact portions 19a and
the cell body contact portions 19b, the connector contact portions
19a, the cell body contact portions 19b, and the connecting
portions 19c being formed in line.
[0055] The Ni foil is made in an already-known electroplating
method, and as shown in the enlarged view of FIG. 12 includes fine
asperities 19e that correspond to ten-point average roughness of
Rz.gtoreq.4 .mu.m in surface roughness on its inside surface that
is oriented inward in a state where the Ni foil is bent 180
degrees. It is to be noted that the state where the connecting
portions 19c are in a U-shape being bent 180 degrees expresses the
state where the cell body contact portions 19b are folded back so
as to cover the connector contact portions 19a.
[0056] It is to be noted that the current collecting members 19 on
the side of the fuel chamber 17 may be made not only of Ni foil but
also of, for example, a porous metal, a wire net, or a wire made
from Ni. In addition, the current collecting members 19 on the side
of the fuel chamber 17 may be made not only from Ni but also from
an Ni alloy, or a metal such as stainless steel that is high
oxidation resistant.
[0057] The current collecting members 19 are produced in the
following method.
[0058] About several tens to one hundred of the current collecting
members 19 (needless to say, the number differs depending on the
size of the fuel chamber) are provided to the fuel chamber 17, and
while they may be individually disposed on to be welded (e.g.,
laser welded and resistance welded) to the interconnector 13, it is
preferable that the above-described Ni foil is processed into a
square flat plate (also referred to as a metallic flat plate) 190
that fits on the fuel chamber 17 as shown in FIG. 10 (b) to make
cutoff lines 19d that correspond to segments 19f consisting of the
cell body contact portions 19b and the connecting portions 19c in
the flat plate 190, and then as shown in the enlarged view of FIG.
9, the connecting portions 19c are bent into a U-shape such that a
cell body contact portion 19b is folded back so as to cover a
connector contact portion 19a while providing space t (see the
enlarged view of FIG. 5) over the connector contact portion 19a.
That is, the connecting portion 19c that is a portion of the
segments 19f is bent into a U-shape such that the cell body contact
portions 19b cover the connector contact portions 19a of the
metallic flat plate 190. In this case, the perforated flat plate
190 that is a remainder after the cell body contact portions 19b
are bent to be raised from the flat plate 190 is an assembly of the
connector contact portions 19a, and in the present embodiment, the
connector contact portions 19a of the flat plate 190 are joined to
the bottom interconnector 13.
[0059] It is to be noted that the above-described cutoff lines 19d
of the current collecting members 19 may be made in the form that
the cell body contact portions 19b and the connecting portions 19c
are integrated in lines as shown in FIG. 11. This form allows the
cell body contact portions 19b and the connecting portions 19c to
be processed efficiently.
[Spacer]
[0060] A Spacer 58 is also provided to the above-described current
collecting members 19 as shown in FIG. 5. In the fuel chamber 17
being located between the cell body 20 and the bottom
interconnector 13, the spacer 58 is disposed between the connector
contact portions 19a and the cell body contact portions 19b so as
to separate the connector contact portions 19a from the cell body
contact portions 19b. Further, the spacer 58 has elasticity in a
thickness direction, and is made from a material such as becoming
larger in thickness by thermal expansion at 700.degree. C. to
1000.degree. C., which falls in the fuel cell operating temperature
region. More specifically, the material of the spacer 58 might be
expanded in a thickness direction by thermal expansion in a way
such that the thickness of the spacer 58 becomes larger than the
above-described space t, which might be also expanded by the
thermal expansion, in order to press the cell body contact portions
19b and the connector contact portions 19a to the respective
contact directions, namely pressing the cell body contact portions
19b toward the cell body 20 while pressing the connector contact
portions 19a toward the interconnector 13.
[0061] It is to be noted that the thickness of the spacer 58 needs
only to be larger than the space t between the cell body contact
portion 19b and the connector contact portion 19a in a state where
the spacer 58 is in the fuel cell operating temperature region;
however, it is preferable to set the thickness of the spacer 58 to
be at least approximately as large as or slightly larger than the
space t between the cell body contact portion 19b and the connector
contact portion 19a in a state where the spacer 58 is at room
temperature at which the fuel cell does not operate. Thus, even
during the time from the start of power generation until the
temperature reaches the fuel cell operating temperature region,
electrical connection between the connector contact portions 19a
and the interconnector 13 and between the cell body contact
portions 19b and the cell body 20 can be stabilized by the spacer
58.
[0062] In addition, a material having elasticity larger than the
current collecting members 19 in the thickness direction is
selected for the spacer 58. The thickness of the spacer 58 greatly
increases or decreases in accordance with the space of the fuel
chamber 17 which changes due to temperature cycle or fuel
pressure/air pressure, compared with the thickness of the current
collecting member 19 that has relatively small elasticity. To be
specific, the spacer 58 shrinks in the thickness direction in
response to shrink of the above-described space of the fuel chamber
17 to exert a buffer function, which turns out preventing the cell
body 20 from cracking, and on the other hand, recovering its
original shape in the thickness direction in response to expansion
of the above-described space to stabilize the electrical
contact.
[0063] In addition, the spacer 58 is made from a material having
properties not to sinter with the current collecting members 19 in
the fuel cell operating temperature region, so that there is no
chance that the cell body contact portions 19b and the connector
contact portions 19a are brought into direct contact with each
other to sinter, which is needless to say, and also the cell body
contact portions 19b and the connector contact portions 19a are
unlikely to sinter through the spacer 58.
[0064] Examples of the material of the spacer 58 that satisfies the
above conditions may include any one kind or a combination of two
or more kinds of mica, alumina felt, vermiculite, carbon fiber,
silicon carbide fiber, and silica.
[0065] In addition, it is preferable that these materials have a
lamination structure of a thin plate-like body such as mica since
appropriate elasticity is provided against a load in a lamination
direction. These materials have a coefficient of thermal expansion
higher than the clamping members 46a to 46d to be described
later.
[0066] It is to be noted that the current collecting members 19
according to the present embodiment are of a monolithic
construction such that the current collecting members 19 are
connected to each other by the flat plate 190 that is an assembly
of the connector contact portions 19a, and in accordance with this
construction, the spacer 58 is made of one material sheet having a
square shape approximately same in width as and slightly shorter
than the flat plate 190 (to be specific, shorter by a length
corresponding to one (the cell body contact portion 19b+ the
connecting portion 19c)), and formed into a transverse lattice
pattern by cutting out the portions as a whole by the line that
correspond to the cell body contact portions 19b and the connecting
portions 19c as shown in FIG. 10(a).
[0067] Then, this spacer 58 is overlaid on the flat plate 190 shown
in FIG. 10(b) where the current collecting members 19 are yet to be
made, and the connecting portions 19c are bent into a U-shape in
that state as shown in the enlarged view of FIG. 9, which can
produce the current collecting members 19 on which the spacer 58 is
mounted in advance. That is, the connecting portions 19c that are
portions of the segments 19f are bent into a U-shape such that the
cell body contact portions 19b cover the connector contact portions
19a of the metallic flat plate 190 via the spacer 58.
[0068] Both the surfaces of the spacer 58 in this state are in
contact with the asperities 19e of the connector contact portions
19a and the asperities 19e of the cell body contact portions 19b as
shown in the enlarged view of FIG. 12 to receive a friction force,
so that the spacer 58 is prevented from being positionally deviated
even when undergoing longitudinal or lateral vibration at the stage
of assembling the fuel cell 3 or the fuel cell stack 8.
Incidentally, while shown in the enlarged view of FIG. 9 is the
cell body contact portions 19b that are bent in stages from the one
that is disposed at the left corner to the right, this drawing is
made mainly in order to explain the working procedure, so that the
bending work of the cell body contact portions 19b may be performed
all together, or may be performed in sequence starting from the
portions convenient for the bending work.
[0069] In addition, in another production method, the
above-described Ni foil is processed into the square metallic flat
plate 190 that fits on the fuel chamber 17 as shown in FIG. 10(b)
to make the plurality of cutoff lines 19d that correspond to the
segments 19f in the flat plate 190. Then, the plurality of segments
19f are bent to be raised in the vertical direction with respect to
the metallic flat plate 190 such that the segments 19f may function
as positioning for sandwiching the spacer 58 as shown in the
enlarged portion A of FIG. 9. The segments 19f need only to be
raised to a degree that positioning of the spacer 58 can be
performed, and are preferably raised in the approximately vertical
state with respect to the flat plate 190. Then, the spacer 58 is
disposed over the entire metallic flat plate 190 where the segments
19f are raised. After disposing the spacer 58, the connecting
portions 19c are subjected to bending work so as to sandwich the
spacer 58 between the connector contact portions 19a and the cell
body contact portions 19b of the segments 19f to produce the
current collecting members 19 on which the spacer 58 is mounted in
advance. In this case, the perforated metallic flat plate 190 that
is a remainder after the segments 19f are bent to be raised from
the metallic flat plate 190 is an assembly of the connector contact
portions 19a.
[0070] In addition, the bending work of the connecting portions 19c
may be performed all together, or may be performed in sequence
starting from the portions convenient for the bending work.
[0071] Further, in another production method, the connecting
portions 19c are bent into a U-shape such that the cell body
contact portions 19b are folded back to cover the connector contact
portions 19a while providing the spaces t (see the enlarged view of
FIG. 5) above the connector contact portions 19a as shown in the
enlarged portion A of FIG. 9 to produce the current collecting
members 19. The spacer 58 is disposed between the cell body contact
portions 19b of these current collecting members 19 and the
connector contact portions 19a to produce the current collecting
members 19 on which the spacer 58 is mounted.
[Air Chamber]
[0072] The above-described air chamber 16 has a square frame shape,
and is formed into a square chamber shape by a conductive thin
metallic separator 23 on the bottom surface of which the
above-described electrolyte 2 is attached and an insulation frame
24 having a frame shape for forming an air electrode gas passage
(hereinafter, also referred to as the "air electrode insulation
frame 24") that is disposed between the separator 23 and the top
interconnector 12 so as to surround the current collecting members
18 as show in FIG. 3 to FIG. 5.
[Current Collecting Members on the Side of the Air Chamber]
[0073] The current collecting members 18 on the side of the air
chamber 16 are made of, for example, stainless steel members that
have the shape of a long thin square log and are dense conductive
members, and the plurality of current collecting members 18 are
disposed in parallel at regular intervals while being in contact
with the air electrode 14 on the upper surface of the electrolyte 2
and the lower surface (inner surface) of the top interconnector 12.
It is to be noted that the current collecting members 18 on the
side of the air chamber 16 may have the structure same as the
current collecting members 19 on the side of the fuel chamber
17.
[0074] As described above, the fuel cell 3 forms the fuel chamber
17 and the air chamber 16 by the combination of the bottom
interconnector 13, the fuel electrode insulation frame 21, the fuel
electrode frame 22, the separator 23, the air electrode insulation
frame 24, and the top interconnector 12, partitions to make the
fuel chamber 17 and the air chamber 16 independent from each other
using the electrolyte 2, and further insulates the side of the fuel
electrode 15 and the side of the air electrode 14 using the fuel
electrode insulation frame 21 and the air electrode insulation
frame 24.
[0075] In addition, the fuel cell 3 includes an air supply unit 25
including the air supply passage 4 for supplying air to the inside
of the air chamber 16, an air discharge unit 26 including the air
discharge passage 5 for discharging the air to the outside from the
air chamber 16, a fuel supply unit 27 including the fuel supply
passage 6 for supplying a fuel gas to the inside of the fuel
chamber 17, and a fuel discharge unit 28 including the fuel
discharge passage 7 for discharging the fuel gas to the outside
from the fuel chamber 17.
[Air Supply Unit]
[0076] The air supply unit 25 includes an air supply through-hole
29 that is opened in the vertical direction in the middle on one
side of the square fuel cell 3, an air supply communication chamber
30 having a long hole shape that is opened in the air electrode
insulation frame 24 so as to communicate with the air supply
through-hole 29, a plurality of air supply communication units 32
each having a concave shape and formed at regular intervals on the
upper surface of a partition wall 31 that partitions the air supply
communication chamber 30 and the air chamber 16, and the
above-described air supply passage 4 that is inserted into and
communicates with the air supply through-hole 29 and is arranged to
supply air to the air supply communication chamber 30 from the
outside.
[Air Discharge Unit]
[0077] The air discharge unit 26 includes an air discharge
through-hole 33 that is opened in the vertical direction in the
middle on one side of the fuel cell 3, the one side being faced to
the air supply unit 25, an air discharge communication chamber 34
having a long hole shape that is opened in the air electrode
insulation frame 24 so as to communicate with the air discharge
through-hole 33, a plurality of air discharge communication units
36 each having a concave shape and formed at regular intervals on
the upper surface of a partition wall 35 that partitions the air
discharge communication chamber 34 and the air chamber 16, and the
above-described air discharge passage 5 having a tube shape that is
inserted into and communicates with the air discharge through-hole
33 and is arranged to discharge air from the air discharge
communication chamber 34 to the outside.
[Fuel Supply Unit]
[0078] The fuel supply unit 27 includes a fuel supply through-hole
37 that is opened in the vertical direction in the middle on one
side of the square fuel cell 3, the one side being one of the two
other sides, a fuel supply communication chamber 38 having a long
hole shape that is opened in the fuel electrode insulation frame 21
so as to communicate with the fuel supply through-hole 37, a
plurality of fuel supply communication units 40 each having a
concave shape and formed at regular intervals on the upper surface
of a partition wall 39 that partitions the fuel supply
communication chamber 38 and the fuel chamber 17, and the
above-described fuel supply passage 6 having a tube shape that is
inserted into and communicates with the fuel supply through-hole 37
and is arranged to supply fuel gas to the fuel supply communication
chamber 38 from the outside.
[Fuel Discharge Unit]
[0079] The fuel discharge unit 28 includes a fuel discharge
through-hole 41 that is opened in the vertical direction in the
middle on one side of the fuel cell 3, the one side being faced to
the fuel supply unit 27, a fuel discharge communication chamber 42
having a long hole shape that is opened in the fuel electrode
insulation frame 21 so as to communicate with the fuel discharge
through-hole 41, a plurality of fuel discharge communication units
44 each having a concave shape and formed at regular intervals on
the upper surface of a partition wall 43 that partitions the fuel
discharge communication chamber 42 and the fuel chamber 17, and the
fuel discharge passage 7 having a tube shape that is inserted into
and communicates with the fuel discharge through-hole 41 and is
arranged to discharge a fuel gas from the fuel discharge
communication chamber 42 to the outside.
[0080] The fuel cell 3 is produced in the following procedure.
[0081] According to the above-described method, the current
collecting members 19 in which the spacer 58 is incorporated are
prepared. In these current collecting members 19, a surface, being
in contact with the spacer 58, of the connector contact portion 19a
has a surface roughness of which ten-point average roughness is
larger than that of a surface, being in contact with the
interconnector 13, of the current collecting member 19. A surface,
being in contact with the spacer 58, of the cell body contact
portion 19b has a surface roughness of which ten-point average
roughness is larger than that of a surface, being in contact with
the cell body 20, of the current collecting member 19.
[0082] The current collecting members 19 on which the spacer 58 is
mounted, and the fuel electrode insulation frame 21 are disposed on
the interconnector 13. Then, the fuel electrode frame 22 is
disposed on the fuel electrode insulation frame 21. The cell body
20 with the separator 23 is disposed such that the cell body 20 is
inserted into the opening inside the frame of the fuel electrode
insulation frame 21 and the fuel electrode frame 22, and such that
at least a portion of the fuel electrode of the cell body is in
contact with the cell body contact portions 19b of the current
collecting members 19. That is, the current collecting members 19
are disposed between the interconnector 13 and the cell body 20,
and the asperities 19e are pressed against the spacer 58. The
ten-point average roughness Rz of the surface roughness of the
asperities 19e is Rz.gtoreq.4 .mu.m on the portions that are in
contact with neither the cell body 20, the interconnector 13, nor
the spacer 58 measures. Measurement on the portions that are not in
contact with neither the cell body 20, the interconnector 13, nor
the spacer 58 means the above-described measurement on the surfaces
of the connecting portions 19c on the sides of the spacer 58 (that
is, the surfaces in the direction same as the sides where the cell
body contact portions 19b are in contact with the spacer 58).
[0083] Then, the air electrode insulation frame 24 is disposed on
the cell body 20 with the separator 23, and then, the
interconnector 12 is disposed on the air electrode insulation frame
24 to produce the fuel cell 3.
[Fuel Cell Stack]
[0084] The fuel cell stack 8 has a configuration such that a
plurality of sets of the above-described fuel cells 3 are stacked
to form a cell group, and the cell group is fixed by the fixing
members 9. It is to be noted that in a case where the plurality of
sets of the fuel cells 3 are stacked, the top interconnector 12 of
the fuel cell 3 that is located lower, and the bottom
interconnector 13 of the fuel cell 3 that is placed on the lower
fuel cell 3 are integrated into one interconnector, and the upper
and lower fuel cells 3 share the one interconnector.
[0085] The above-described fixing members 9 are combinations of a
pair of end plates 45a and 45b for sandwiching the cell group
vertically, and four pairs of the clamping members 46a to 46d for
clamping the end plates 45a and 45b to the cell group by inserting
bolts into corner holes (not illustrated) of the end plates 45a and
45b and the above-described corner through-holes 47, 47 to fasten
them with nuts. Examples of the material of the clamping members
46a to 46d include Inconel 601.
[0086] The above-described air supply passage 4 is mounted so as to
penetrate through-holes (not illustrated) of the endplates 45a and
45b and the air supply through-holes 29 of the cell group in the
vertical direction with respect to the fuel cell stack 8, and the
end portion of the tubular passage is closed while lateral holes 48
are provided as shown in FIG. 7 so as to each correspond to the air
supply communication chambers 30, whereby air is supplied to the
air supply communication chambers 30 via the lateral holes 48.
[0087] In a similar manner, the air discharge passage 5 takes in
the air from lateral holes 49 each corresponding to the air
discharge communication chambers 34 to discharge the air to the
outside, the fuel supply passage 6 supplies a fuel gas from lateral
holes 50 each corresponding to the fuel supply communication
chambers 38 as shown in FIG. 8, and the fuel discharge passage 7
takes in the fuel gas from lateral holes 51 each corresponding to
the fuel discharge communication chambers 42 to discharge the fuel
gas to the outside.
[Container]
[0088] The container 10 for housing the fuel cell stack 8 has heat
resistance and sealed structure, and includes two half bodies 53a
and 53b that include flanges 52a and 52b on their opening portions
and are joined together so as to face each other as shown in FIG.
1. The bolts of the above-described clamping members 46a to 46d
project from the top of this container 10 to the outside, and the
nuts 54 are screwed onto the projecting portions of these clamping
members 46a to 46d to fix the fuel cell stack 8 inside the
container 10. In addition, the air supply passage 4, the air
discharge passage 5, the fuel supply passage 6, and the fuel
discharge passage 7 also project to the outside from the top of the
container 10, and sources for supplying air and a fuel gas and the
like are connected to the above-described projecting portions.
[Output Members]
[0089] The output members 11 for outputting electricity generated
by the fuel cell stack 8 define the clamping members 46a to 46d on
the corner portions of the fuel cell stack 8, and the endplates 45a
and 45b, electrically connect the pair of clamping members 46a and
46c that diagonally face each other with the top endplate 45a that
is a positive electrode, and electrically connect the other pair of
clamping members 46b and 46d with the bottom end plate 45b that is
a negative electrode. As a matter of course, the clamping members
46a and 46d connected with the positive electrode and the clamping
members 46b and 46c connected with the negative electrode are
insulated from the endplate 45a (45b) of the other electrodes by
making metallic washers 55 intervene (FIG. 1), and are insulated
from the fuel cell stack 8 by providing clearance between the
clamping members 46a to 46d and the corner through-holes 47. Thus,
the clamping members 46a and 46c of the fixing members 9 function
also as output terminals of the positive electrode that are
connected to the top end plate 45a, and the other clamping members
46b and 46d function also as output terminals of the negative
electrode that are connected to the bottom end plate 45b.
[Power Generation]
[0090] When air is supplied to the air supply passage 4 of the
above-described fuel cell stack structure 1, the air flows in a
direction from right to left of FIG. 7, is supplied to the air
chambers 16 through the air supply units 25 including the air
supply passage 4, the air supply communication chambers 30, and the
air supply communication units 32 that are on the right side,
passes through gas passages 56 among the current collecting members
18 of the air chambers 16, and is further discharged to the outside
through the air discharge units 26 including the air discharge
communication units 36, the air discharge communication chambers
34, and the air discharge passage 5.
[0091] At the same time, When hydrogen as an example of a fuel gas
is supplied to the fuel supply passage 6 of the fuel cell stack
structure 1, the fuel gas flows in a direction from the top to the
bottom of FIG. 8, and is supplied to the fuel chambers 17 through
the fuel supply units 27 including the fuel supply passage 6
located on the top side, the fuel supply communication chambers 38,
and the fuel supply communication units 40. The fuel gas further
passes with being diffused through gas passages 57 (see the
non-shaded area in the fuel chamber 17 in FIG. 8), which are formed
between the current collecting members 19, 19 . . . , more strictly
to say, formed between the cell body contact portions 19b, 19b . .
. , to be discharged to the outside through the fuel discharge
units 28 including the fuel discharge communication units 44, the
fuel discharge communication chambers 42, and the fuel discharge
passage 7.
[0092] It is to be noted that if the current collecting members 19
are made of a porous metal, a wire net, or a wire as described
above, the surfaces of the gas passages 57 become uneven to improve
the diffuseness of the fuel gas.
[0093] Raising the temperature inside of the above-described
container 10 to 700.degree. C. to 1000.degree. C. by
supplying/discharging air and a fuel gas in this manner causes the
air and the fuel gas to initiate a reaction via the air electrodes
14, the electrolytes 2, and the fuel electrodes 15, so that
direct-current electrical energy is generated with the air
electrodes 14 functioning as positive electrodes while the fuel
electrodes 15 functioning as negative electrodes. It is to be noted
that the principle of how electrical energy is generated in the
fuel cell 3 is known, the explanation of which is omitted.
[0094] The air electrodes 14 are electrically connected to the top
interconnectors 12 through the current collecting members 18 while
the fuel electrodes 15 are electrically connected to the bottom
interconnectors 13 through the current collecting members 19 as
described above, and the fuel cell stack 8 is in a state where the
plurality of the fuel cells 3 are stacked to be connected in series
to each other, so that the top end plate 45a becomes a positive
electrode while the bottom end plate 45b becomes a negative
electrode, and the electrical energy can be taken out to the
outside via the clamping members 46a to 46d that function also as
output terminals.
[0095] As described above, a fuel cell repeats temperature cycles
such that the temperature rises during power generation and falls
when power generation stops. Hence, also all the constituent
members of the fuel chambers 17 and the air chambers 16, and the
above-described clamping members 46a to 46d are thermally expanded
and shrunk repeatedly, and accordingly the spaces of the fuel
chambers 17 and the air chambers 16 are expanded and shrunk
repeatedly.
[0096] In addition, also the fuel pressure or the air pressure
sometimes fluctuates, so that the spaces of the fuel chambers 17 or
the air chambers 16 are expanded or shrunk also by deformation of
the cell bodies 20 due to the fluctuations of the pressure.
[0097] In accordance with the change in the expansion direction of
the fuel chambers 17 and the air chambers 16, the current
collecting members 19 on the side of the fuel chambers 17 press the
cell bodies 20 mainly by the thermal expansion in the same
direction as the elasticity in the stacking direction of the
spacers 58 (the thickness direction or the clamping direction of
the clamping members 46a to 46d) in the present embodiment, so that
electrical connection can be maintained stably.
[0098] It is to be noted that the pressure of the cell bodies 20 by
the current collecting members 19 has an effect also on the side of
the air chambers 16, so that electrical connection of the air
chambers 16 can be maintained stably, too.
[0099] In addition, in accordance with the change in the shrinkage
direction of the fuel chambers 17 and the air chambers 16, the
stress applied onto the cell bodies 20 is reduced mainly by the
shrinkage of the spacers 58 on the side of the fuel chambers
17.
[0100] In addition, if the current collecting members 19 on the
side of the fuel electrodes 15 are made from Ni or an Ni alloy, the
cell body contact portions 19b are diffused and joined to be
integrated with Ni in the fuel electrodes 15 in the high
temperature environment during power generation.
[0101] Thus, electrical connection by the current collecting
members 19 can be maintained stably.
[0102] It is preferable to coat the fuel electrodes 15 with an NiO
paste to form joining layers.
[0103] The NiO thus becomes Ni when applying current in H2, so that
joining characteristics of the current collecting members 19 and
the fuel electrodes 15 are further improved.
[0104] The above-described joining layers may be formed by coating
the fuel electrodes 15 with a Pt paste.
[0105] In addition, while the flat plate 190 that is an assembly of
the connector contact portions 19a is welded to be joined to the
bottom interconnector 13 in the present embodiment, if the
materials for the interconnector 13 and the flat plate 190 are a
combination of materials capable of being diffused and joined
together in the high temperature environment during power
generation (e.g., Crofer22H and Ni), or if the joining layer
described above is formed on the inside surface of the bottom
interconnector 13, the interconnector 13 and the current collecting
members 19 can be joined to be integrated together in the high
temperature environment during power generation.
[0106] The foregoing description of the embodiment of the present
invention has been presented; however, it is not intended to be
exhaustive or to limit the present invention to the above-described
embodiment. For example, while the fine asperities 19e are formed
on the outside surfaces by using Ni foil (metallic foil) made in
the electroplating method as the current collecting members 19 in
the present embodiment, the above-described asperities 19e may be
formed by subjecting a metallic foil to known sandblasting or
etching in which alumina particles are smashed into one surface of
the metallic foil that is rolled by a reduction roll or the
like.
REFERENCE SIGNS LIST
[0107] 1 . . . Fuel cell stack structure [0108] 2 . . . Electrolyte
[0109] 3 . . . Fuel cell [0110] 8 . . . Fuel cell stack [0111] 12,
13 . . . Interconnectors [0112] 14 . . . Air electrode [0113] 15 .
. . Fuel electrode [0114] 18, 19 . . . Current collecting members
[0115] 19a . . . Connector contact portion [0116] 19b . . . Cell
body contact portion [0117] 19c . . . Connecting portion [0118] 19e
. . . Asperities [0119] 19f . . . Segment [0120] 20 . . . Cell body
[0121] 46a to 46d . . . Clamping members [0122] 58 . . . Spacer
[0123] 61 . . . Front surface [0124] 62 . . . Back surface [0125]
190 . . . Metallic flat plate
* * * * *